"When did you know you were trans?" Does this moment exist?

"When did you first know you were trans?" I get these kinds of questions a lot, actually. It kind of makes sense, as this is a common question for hobbies and lifestyle choices. "How long have you been training in aikido?" "Oh, you're vegan? How long have you been vegan?"

But it's a little different for trans-ness. For some people, including myself, "How long have you been trans?" doesn't make much sense.

While I might be able to figure out when I first attended an aikido class and calculate from that date, I don't have a "being trans" anniversary.